Southern California's Ontario International Airport (ONT) in April posted its highest number of international passengers in a single month in the airport's history, signaling the fast-growing gateway is in for a busy summer travel season.

More than 34,000 international air travelers moved through ONT last month, an increase of 138% over April a year ago. At the same time, ONT welcomed almost 500,000 domestic fliers, 7.5% more than last year.

Overall, passenger traffic rose 11.6% in April to more than 530,000, extending ONT's run of double-digit increases.

Ontario officials also reported strong passenger figures on a year-to-date basis. The total number of air passengers increased 15% to 1.87 million, with the number of domestic travelers 12.6% higher at 1.76 million and international passengers up 85.7% to more than 104,000.

"At a time when many California airports are struggling to restore international services, Ontario is experiencing strong growth and we expect that trend to continue in the coming months," said Atif Elkadi, chief executive officer, Ontario International Airport Authority (OIAA). "And while our terminals will continue to be busy, passengers can expect our popular and hassle-free experience with reasonably priced parking, easy access to terminals, clean and light-filled facilities, efficient security screening and first-rate dining options."

Shipments of commercial freight and mail totaled more than 58,000 tons, a decrease of 12.7%, consistent with industry trends. Over the first four months of the year, cargo volume declined nearly 10% to 243,000 tons compared with the same period last year.